Cannot make outgoing calls over the internet

You cannot use a telephone or telephones connected to the FRITZ!Box to make calls over the internet. This may also only occur with certain numbers you attempt to call. The problem either occurs sporadically or continuously. When it occurs, the telephone number may not be currently registered and one of the following error messages or a different message referring to the telephone number may be displayed in the event log of the FRITZ!Box:

If the status LED is still gray, contact your internet telephony provider to have your telephone number and account information checked.

5 The provider rejects the call attempt

This section only applies if the message "Internet telephony [...] failed. Reason for error: Not Acceptable Here (488)" is displayed under "System > Event Log" in the FRITZ!Box user interface when the error occurs. This message from your provider indicates that it does not make a requested function available for your line. This may be due to the following reasons, for example:

The provider does not support the requested codec.

The provider does not permit calls to the destination number, for example calls to premium numbers.

The provider does not allow you to make simultaneous calls.

Therefore, the FRITZ!Box cannot resolve this issue.

6 Setting up the FRITZ!Box to conduct calls over another router

The following steps are only necessary if the FRITZ!Box does not establish its own connection to the internet, but instead shares the internet connection of another router in the network:

7 Setting your analog telephone to tone dialing

Set your device to "tone dialing" (DTMF) and not "pulse dialing". If tone dialing is selected, you will hear a tone when you press a number key; with pulse dialing, you hear clicking sounds. Refer to the device's manufacturer for information on how to set it up, for example consult the manual.

8 Connecting and configuring an ISDN telephone

The following steps are only necessary if the telephone is connected to the "FON S0" port:

Preparations

Configure the devices so that you can send keypad sequences (sequences of symbols and digits, such as *121#) and enter special characters such as * and # with them. With many telephones, you can use the menu "Operation at a PBX > Dialing options > Dial * and #" to configure this.

Disabling the transmission of text information on your ISDN telephone

When making calls with an ISDN telephone, the FRITZ!Box sends certain text information to the telephone. This way you can see on the display of your telephone which number is being used to make the call, for example. However, some ISDN telephones cannot process this text information properly. Therefore, disable the function in the FRITZ!Box for testing purposes:

Enter #960*0* on your telephone and press the call key (lift the receiver).

Hang up again after about 3 seconds.

Note:You can re-enable this function by entering #960*2*.

Disabling the energy-saving mode on your ISDN telephone

The FRITZ!Box is equipped with a number of energy-saving mechanisms. For example, when idle, the internal S0 bus of the FRITZ!Box terminates communication between it and the ISDN device. Some ISDN devices have problems with this function. Therefore, disable this function in the FRITZ!Box if you experience problems when establishing connections with ISDN devices:

Enter #966*1* on your telephone and press the call key (lift the receiver).

Hang up again after about 3 seconds.

Note:You can re-enable this function by entering #966*0*.

Resetting the ISDN telephone

On the telephone, delete all numbers (MSNs), all call-by-call prefixes, and all dialing rules.

Connecting a single ISDN telephone

Disconnect all devices (such as telephones, PBXs, faxes) and cables from the "FON S0" port.

Connect a telephone to the "FON S0" port. Do not connect the telephone to the FRITZ!Box by means of a PBX or an ISDN hub.

If you cannot make calls, proceed with the following section. Do not connect any further ISDN devices yet.

If you can make calls, then another device or its cable is defective, or a device is incorrectly configured, for example incorrect telephone numbers, dialing rules.

Reconnect the other ISDN devices to find out which device was causing the problem. Do not connect more than one ISDN device without its own power supply.

If the error occurs again after you connect a different ISDN telephone, then your telephone or its cable is defective.

If the error occurs again after you connect a PBX, then the PBX is either defective or incorrectly configured, for example incorrect telephone numbers, incorrect dialing rules, or call-by-call prefixes.

9 Setting up FRITZ!App Fon

The following steps are only necessary if the problem occurs when using FRITZ!App Fon: